You can lose weight on any diet as long as you stick to it...
A comparison of four popular diet plans finds that the key to losing weight
may not be which diet plan a person picks, but sticking with the plan that
is chosen.
The study
also found that popular diets can be effective for modest weight loss and
reducing several cardiac risk factors, but overall adherence rates were low.
In this one year study, Michael L. Dansinger, M.D., of Tufts-New England Medical
Center, Boston, and colleagues assessed adherence rates and the effectiveness
of four popular diets for weight loss and cardiac risk factor reduction.
The
diets and their principle weight loss strategies were: Weight Watchers (restriction
of portion sizes and calories); Atkins (minimize carbohydrate intake without
fat restriction); Zone (modulate macronutrient balance and glycemic load);
and Ornish (restrict fat).
This trial included 160 overweight or obese adults aged 22 to 72 years, with
known hypertension, dyslipidemia (high cholesterol), or fasting hyperglycemia
(high blood sugar). Forty participants were
assigned to each of the diet plans. After 2 months of maximum effort, participants
selected their own levels of dietary adherence.
Assuming no change from baseline for participants who discontinued the study,
the researchers found that average weight loss at 1 year was:
- 4.6 pounds for
Atkins (53% of 40 subjects completed)
- 7.1 pounds for Zone (65% of
40 subjects completed)
- 6.6 pounds for Weight Watchers
(65% of 40 subjects completed)
- 7.3 pounds for Ornish (50% of 40 subjects completed).
Amount of weight loss was associated with self-reported dietary adherence
level but not with diet type.
For each diet, decreasing levels of total/HDL cholesterol, C-reactive protein,
and insulin were significantly associated with weight loss with no significant
difference between diets.
All 4 diets resulted in modest statistically significant weight loss at
1 year, with no statistically significant differences between diets.
In each diet group, approximately 25 percent of the initial participants
sustained a 1-year weight loss of more than 5 percent of initial body weight
and approximately 10 percent of participants lost more than 10 percent of
body weight.
"We found that a variety of popular diets can reduce weight and several
cardiac risk factors under realistic clinical conditions," conclude the authors,
"but only for the minority of individuals who can sustain a high dietary adherence
level."
"Despite
a substantial percentage of participants who could sustain meaningful adherence
levels, no single diet produced satisfactory adherence rates and the progressively
decreasing mean adherence scores were practically identical among the 4 diets.
The higher discontinuation rates for the Atkins and Ornish diet groups suggest
many individuals found these diets to be too extreme," the
authors write.
"One way to improve dietary adherence rates in clinical practice may be to
use a broad spectrum of diet options, to better match individual patient food
preferences, lifestyles, and cardiovascular risk profiles.
"Participants in
our study were not allowed to choose their dietary assignment; however we
suspect adherence rates and clinical improvements would have been better if
participants had been able to freely select from the 4 diet options."
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Reference
Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. (2005). Comparison
of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and
heart disease risk reduction: a randomized trial. Journal
of the America Medical Association, 293, 43-53
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